package com.tangding.common.utils;


/**
 * @description 
 *
 * @author Ranger
 * @version 2017年12月12日_下午7:19:02
 *
 */
public class ByteUtil {  
    /** 
     * 转换short为byte 
     *  
     * @param b 
     * @param s 
     *            需要转换的short 
     * @param index 
     */  
    public static void putShort(byte b[], short s, int index) {  
        b[index + 1] = (byte) (s >> 8);  
        b[index + 0] = (byte) (s >> 0);  
    }  
  
    /** 
     * 通过byte数组取到short 
     *  
     * @param b 
     * @param index 
     *            第几位开始取 
     * @return 
     */  
    public static short getShort(byte[] b, int index) {  
        return (short) (((b[index + 1] << 8) | b[index + 0] & 0xff));  
    }  
    
    /** 
     * 转换int为byte数组 
     *  
     * @param bb 
     * @param x 
     * @param index 
     */  
    public static void putInt(byte[] bb, int x, int index) {  
        bb[index + 3] = (byte) (x >> 24);  
        bb[index + 2] = (byte) (x >> 16);  
        bb[index + 1] = (byte) (x >> 8);  
        bb[index + 0] = (byte) (x >> 0);  
    }  
  
    /** 
     * 通过byte数组取到int 
     *  
     * @param bb 
     * @param index 
     *            第几位开始 
     * @return 
     */  
    public static int getInt(byte[] bb, int index) {  
        return (int) ((((bb[index + 3] & 0xff) << 24)  
                | ((bb[index + 2] & 0xff) << 16)  
                | ((bb[index + 1] & 0xff) << 8) | ((bb[index + 0] & 0xff) << 0)));  
    }  
  
    /** 
     * 转换long型为byte数组 
     *  
     * @param bb 
     * @param x 
     * @param index 
     */  
    public static void putLong(byte[] bb, long x, int index) {  
        bb[index + 7] = (byte) (x >> 56);  
        bb[index + 6] = (byte) (x >> 48);  
        bb[index + 5] = (byte) (x >> 40);  
        bb[index + 4] = (byte) (x >> 32);  
        bb[index + 3] = (byte) (x >> 24);  
        bb[index + 2] = (byte) (x >> 16);  
        bb[index + 1] = (byte) (x >> 8);  
        bb[index + 0] = (byte) (x >> 0);  
    }  
  
    /** 
     * 通过byte数组取到long 
     *  
     * @param bb 
     * @param index 
     * @return 
     */  
    public static long getLong(byte[] bb, int index) {  
        return ((((long) bb[index + 7] & 0xff) << 56)  
                | (((long) bb[index + 6] & 0xff) << 48)  
                | (((long) bb[index + 5] & 0xff) << 40)  
                | (((long) bb[index + 4] & 0xff) << 32)  
                | (((long) bb[index + 3] & 0xff) << 24)  
                | (((long) bb[index + 2] & 0xff) << 16)  
                | (((long) bb[index + 1] & 0xff) << 8) | (((long) bb[index + 0] & 0xff) << 0));  
    }  
  
    /** 
     * 字符到字节转换 
     *  
     * @param ch 
     * @return 
     */  
    public static void putChar(byte[] bb, char ch, int index) {  
        int temp = (int) ch;  
        // byte[] b = new byte[2];  
        for (int i = 0; i < 2; i ++ ) {  
            bb[index + i] = new Integer(temp & 0xff).byteValue(); // 将最高位保存在最低位  
            temp = temp >> 8; // 向右移8位  
        }  
    }  
  
    /** 
     * 字节到字符转换 
     *  
     * @param b 
     * @return 
     */  
    public static char getChar(byte[] b, int index) {  
        int s = 0;  
        if (b[index + 1] > 0)  
            s += b[index + 1];  
        else  
            s += 256 + b[index + 0];  
        s *= 256;  
        if (b[index + 0] > 0)  
            s += b[index + 1];  
        else  
            s += 256 + b[index + 0];  
        char ch = (char) s;  
        return ch;  
    }  
  
    /** 
     * float转换byte 
     *  
     * @param bb 
     * @param x 
     * @param index 
     */  
    public static void putFloat(byte[] bb, float x, int index) {  
        // byte[] b = new byte[4];  
        int l = Float.floatToIntBits(x);  
        for (int i = 0; i < 4; i++) {  
            bb[index + i] = new Integer(l).byteValue();  
            l = l >> 8;  
        }  
    }  
  
    /** 
     * 通过byte数组取得float 
     *  
     * @param bb 
     * @param index 
     * @return 
     */  
    public static float getFloat(byte[] b, int index) {  
        int l;  
        l = b[index + 0];  
        l &= 0xff;  
        l |= ((long) b[index + 1] << 8);  
        l &= 0xffff;  
        l |= ((long) b[index + 2] << 16);  
        l &= 0xffffff;  
        l |= ((long) b[index + 3] << 24);  
        return Float.intBitsToFloat(l);  
    }  
  
    /** 
     * double转换byte 
     *  
     * @param bb 
     * @param x 
     * @param index 
     */  
    public static void putDouble(byte[] bb, double x, int index) {  
        // byte[] b = new byte[8];  
        long l = Double.doubleToLongBits(x);  
        for (int i = 0; i < 4; i++) {  
            bb[index + i] = new Long(l).byteValue();  
            l = l >> 8;  
        }  
    }  
  
    /** 
     * 通过byte数组取得float 
     *  
     * @param bb 
     * @param index 
     * @return 
     */  
    public static double getDouble(byte[] b, int index) {  
        long l;  
        l = b[0];  
        l &= 0xff;  
        l |= ((long) b[1] << 8);  
        l &= 0xffff;  
        l |= ((long) b[2] << 16);  
        l &= 0xffffff;  
        l |= ((long) b[3] << 24);  
        l &= 0xffffffffl;  
        l |= ((long) b[4] << 32);  
        l &= 0xffffffffffl;  
        l |= ((long) b[5] << 40);  
        l &= 0xffffffffffffl;  
        l |= ((long) b[6] << 48);  
        l &= 0xffffffffffffffl;  
        l |= ((long) b[7] << 56);  
        return Double.longBitsToDouble(l);  
    }  
}  